Annular elastomeric articles such as inner tubes for pneumatic tires are molded in heated molds which are provided with a gate for receiving a valve stem which is bonded to the inner tube during the molding procedure. These valve stems usually are rubber covered stems used for passenger vehicle tires or may be various sizes and configurations of brass stems used for large truck tires. A single size tire and in particular the inner tubes therefor may have various valve stem positions depending upon the particular application in which the inner tubes are intended for use. Heretofore each inner tube valve stem location required a separate gate which had to be built and maintained in inventory and precision ground to fit a specific mold. Thus, when inner tubes with different valve positions or offsets as referred to in the molding art, were cured in the same mold, a complete gate change had to be made for each separate valve stem location. This gate change required time consuming delays and operating procedures and increased setup time. These multiple gates also required that each gate had to be ground and refitted to the inner tube cavity after periodic recutting of the cavity, again requiring increased downtime and subsequent setup time.
Examples of prior art in the inner tube mold curing art and associated valve stems are shown in U.S. Pat. Nos. 2,689,377; 3,819,791 and 4,010,052. None of these prior art molds and valve stem insertion apparatus and procedures disclose or suggest any solution to the problem of gate replacement for each different valve stem offset or angular position in the final molded inner tube.
There is no known apparatus or device of which I am aware which enables valve stems having different offset or angular positions to be molded or bonded to an inner tube during the molding of the inner tube in a single valve stem gate.